1. Field of the Invention
The present invention relates to a gas sensor element, and to a gas sensor including the gas sensor element.
2. Description of the Related Art
A conventionally known gas sensor is attached to an exhaust path of an internal combustion engine such as an automotive engine for detecting a concentration of oxygen or a concentration of NOx in exhaust gas (gas to be measured) (refer to Patent Documents 1 and 2). Patent Documents 1 and 2 describe a gas sensor element used in the gas sensor and configured such that a plurality of platelike solid electrolyte bodies are laminated together. The gas sensor element includes electrodes provided on the front sides or back sides of the solid electrolyte bodies, and leads provided on the front sides or back sides of the solid electrolyte bodies and connected to the electrodes.
In Patent Documents 1 and 2, in order to ensure oxygen pumping performance, the electrodes are porous; as a result, the electrodes have gas permeability and water permeability. In contrast, the leads are formed to be dense since, in order to improve electrical conductivity, high density per unit area is desired. As a result, the leads are gas-impermeable and water-impermeable.
[Patent Document 1] Japanese Patent No. 4165652
[Patent Document 2] Japanese Patent Application Laid-Open (kokai) No. 2010-122187